Janusz Andrzej Zajdel (born on August 15, 1938 in Warsaw - July 19, 1985 in Warsaw, Poland) was a Polish science fiction author. His bibliography includes, apart from numerous short stories and short novels:

• Cylinder van Troffa (1980)
• Limes inferior (1982)
• Cala prawda o planecie Ksi (1983)
• Wyjscie z cienia (1983)
• Paradyzja (1984)

These books created the core of Polish social fiction. In his books he envisions totalitarian states and collapsed societies. His heroes are desperately trying to find sense in world around them, sometimes (like in Cylinder van Troffa) they are outsiders from a different time or place, trying to adapt to the new environment.

Named after him is the Zajdel, award of Polish fandom.

See also science fiction authors.